import java.util.Stack;

//牛客232. 用栈实现队列
class MyQueue {
    private Stack<Integer> s1;
    private Stack<Integer> s2;

    public MyQueue() {
        s1 = new Stack<>();
        s2 = new Stack<>();

    }
    
    public void push(int x) {
            s1.push(x);
    }
    
    public int pop() {
        if(s2.empty()){
            while(!s1.empty()) {
                s2.push(s1.pop());
            }
        }
        return s2.pop();
    }
    

        public int peek() {
            if(s2.empty()){
                while(!s1.empty()){
                    s2.push(s1.pop());
                }
            }
            return s2.peek();
        }
    

        public boolean empty() {
            return s1.empty() && s2.empty();
        }
}
